To prepare for the ETH 2.0 upgrade, DigiFinex introduced two temporary $ETH tokens. $ETHS (ETHPoS) represents the token for the new PoS (Proof-of-Stake) chain. $ETHW (ETHPoW) represents the token for the PoW (proof-of-Work) chain that will potentially continue to exist.
If the ETH 2.0 ends up with more than one chain, $ETHS will be automatically converted into the upgraded $ETH at a 1:1 ratio and the $ETHS will be delisted, and the PoW chain with the most hashrate will serve as the main chain of $ETHW.
If the hard fork ends up failing, $ETHS will be automatically converted into the update $ETH, and the $ETHS and $ETHW will be delisted all together.